Pitavastatin calcium has an activity to specifically and antagonistically inhibit HMG-CoA reductase which is a rate determining enzyme of cholesterol synthesis, and is used for the treatment of hypercholesterolemia, familial hypercholesterolemia and the like.
Pitavastatin calcium has a chemical name: bis[(3R,5S,6E)-7-[2-cyclopropyl-4-(4-fluorophenyl)-3-quinolyl]-3,5-dihydroxy-6-heptenoate]-calcium represented by the following formula:

It is known that pitavastatin calcium can be produced by hydrolyzing a precursor compound thereof, 2-[(4R,6S)-6-[(E)-[2-cyclopropyl-4-(4-fluorophenyl)-3-quinolyl]vinyl]-2,2-dimethyl-1,3-dioxan-4-yl]acetate ester represented by the following formula (16):
wherein R7 is an alkyl group having a carbon number of 1-4.
A compound represented by the formula (16) can be obtained by a Wittig reaction.
Patent document 1 describes that the above-mentioned compound represented by the formula (16) can be obtained by reacting a condensed pyridine derivative and an aldehyde compound in the presence of n-butyllithium at −78° C.
The method described in patent document 1 requires a special facility for industrial production since the reaction is performed at an extremely low temperature of −78° C., and the yield thereof is low. In addition, since n-butyllithium, which is liable to ignite easily, is used as a base, there is concern about safety in industrial-scale production. Furthermore, since n-butyllithium and phosphorus tribromide used for the reaction are expensive, the cost becomes high.
Patent document 2 describes that the above-mentioned compound represented by the formula (16) is obtained by reacting a compound represented by the following formula (17):
wherein R7 is as defined above and a compound represented by the following formula (18):
wherein R8 is an aryl group, aralkyl group or alkyl group, in the presence of an alkali metal salt.
The method described in patent document 2 has an insufficient yield for industrial production. In addition, the compound represented by the formula (17) and the compound represented by the formula (18) require multistep process for synthesis, which produces concern about the costs.